Acanmontanoside, a new phenylethanoid diglycoside from Acanthus montanus

A new phenylethanoid glycoside acylated with syringic acid, namely acanmontanoside, was isolated from the aerial portions of Acanthus montanus (Nees). T. Anderson, along with decaffeoylverbascoside, verbascoside, isoverbascoside, leucosceptoside A, (2R)-2-O-?-D-glucopyranosyl-2H-1,4-benzoxazin-3(4H)-one (HBOA-Glc), (2R)-2-O-?-D-glucopyranosyl-4-hydroxy-2H-1,4-benzoxazin-3(4H)-one (DIBOA-Glc), (3R)-1-octen-3-ol-3-O-?-D-xylopyranosyl-(1→6)-O-?-D-glucopyranoside and ebracteatoside B. The structure elucidations were based on physical data and spectroscopic analyses including 1D- and 2D-NMR.     

A novel synthesis of Aporhoeadanes

A one-pot synthesis of aporhoeadanes from the reaction of 3,4-dihydro-isoquinolines, 2-chloromethylbenzoyl chloride and sodium hydroxide, is described.     

The structure of an aminosilane coupling agent in aqueous solutions and partially cured solids

The molecular structures of partially cured polyaminopropylsilsesquioxane and aminopropyltriethoxysilane in water have been studied using Fourier-transform infrared, laser Raman, and quasielastic laser light-scattering spectroscopy. A multiply hydrogen-bonded structure is proposed for the intramolecularly interacting amine and silanol groups on the basis of isotope exchange experiment and conformational energy calculations. Conformational restrictions are rather low for the proposed structure, which is thus suitable for the partially cured solid where there are slight perturbations by the surrounding amine and silanol groups. The O.…N distance was experimentally determined to be in the range 2.70–2.67 Å and estimated theoretically as 2.49–2.45 Å. The aminosilane in very dilute solution is found to be mostly monomeric. The isolated monomer-oligomer transition lies around 0.15% by weight and this transition influences the amount of silane uptake by glass fibers. It is also proposed that this phenomenon may be general for surface treatments by silane coupling agents. Hydrolyzed aminosilane oligomers exist in part as submicron aggregates which can be broken up by the addition of an alcohol. The neutralized aminosilane hydrolyzes very slowly although it dissolves in water instantaneously. Micelle formation is also proposed.     

Phenylethanoid and iridoid glycosides from the Thai medicinal plant, Barleria strigosa

A phenylethanoid (4-hydroxyphenylethyl 4-O-beta-D-glucopyranosyl-(1-->3)-O-alpha-L-rhamnopyranoside) and an iridoid (10-O-trans-coumaroyl-eranthemoside) were isolated from an entire Barleria strigosa plant together with verbascoside, isoverbascoside, decaffeoylverbascoside, (+)-lyoniresinol 3alpha-O-beta-D-glucoside, apigenin 7-O-alpha-L-rhamnosyl-(1-->6)-O-beta-D-glucoside, 7-O-acetyl-8-epi-loganic acid and (3R)-1-octen-3-ol-3-O-beta-D-xylosyl-(1-->6)-beta-D-glucoside. The structural elucidations were based on analyses of physical and spectroscopic data.     

Ziziphine N, O, P and Q, new antiplasmodial cyclopeptide alkaloids from Ziziphus oenoplia var. brunoniana

Bioassay-guided fractionation of the EtOAc extract of the roots of Thai Ziziphus oenoplia var. brunoniana resulted in the isolation of four new 13-membered cyclopeptide alkaloids of the 5(13) type, ziziphine N-Q. The structures of the new metabolites were elucidated on the basis of spectroscopic analyses and the stereochemical assignments were established by comparison with other related compounds of known stereochemistry. Ziziphine N and Q exhibited significant antiplasmodial activity against the parasite Plasmodium falciparum with the inhibitory concentration (IC₅₀) values of 3.92 and 3.5 μg/mL, respectively. Ziziphine N and Q also demonstrated weak antimycobacterial activity against Mycobacterium tuberculosis with the same MIC value of 200 μg/mL.     

DEPOLYMERIZATION AND KINETICS OF DEPOLYMERIZATION OF POLYETHYLENE TEREPHTHALATE USING DIBUTYLTIN OXIDE CATALYST

Depolymerization of poly（ethylene terephthalate） （PET） was performed in the tubular bomb microreactor which contained the solution of PET in methanol and dibutyltin oxide at the temperature ranging from 433 K to 473 K, the reaction time from 5 to 45 min and the catalyst-to-PET ratio of 0.3%-2% by weight. The optimal condition for PET depolymerization catalyzed by dibutyltin oxide is the temperature of 443-453 K, the reaction time of 20-25 min and 0.8% by weight of catalyst. By using differential methods, the activation energy for the depolymerization process was found to be 154.05 kJ/mol in the temperature range from 433-463 K.     

A convenient synthesis of 8-oxoprotoberberine derivatives

The annulation of isoquinoline derivatives to form the 8-oxoprotoberberine derivatives is described. The key step of the reaction involves intramolecular alkylation of the Reissert compounds.     

Ultrastructure of the ommatrichia in Megaselia scalaris (Loew) (Diptera: Phoridae)

Using both scanning electron microscopy (SEM) and transmission electron microscopy (TEM), the ommatrichia, or hair-like processes that are located between the facets of the compound eye, were examined on an adult male Megaselia scalaris (Loew) fly. Each ommatrichium was observed to be a tapering structure bearing a longitudinally grooved cuticle and are anchored tightly in flexible sockets. Ultrathin sectioning and TEM revealed a thick wall in the ommatrichia, and their function was proposed to be mechanoreception based on characteristics from both SEM and TEM observations.